from manim import *



class math2(MovingCameraScene):
    def construct(self):
        self.camera.background_color = BLACK  # 设置背景颜色
        self.camera.frame_width = 100  # 设置边框宽度
        self.camera.frame_height = 60  # 设置边框高度
        self.camera.pixel_height = 1080  # 设置像素高度
        self.camera.pixel_width = 1920  # 设置像素宽度
        self.camera.center = ORIGIN  # 设置中心点位置
        self.camera.scale_factor = 1.0  # 设置缩放因子
        #设置横线
        for i in range(6*2+1):       
            dot1=Dot([-50,5*(i-6),0]).set_opacity(0.5)
            dot2=Dot([50,5*(i-6),0]).set_opacity(0.5)
            if i==6:
                line1=Line(dot1,dot2).set_color(WHITE).set_opacity(0.5)
                
            else:
                line1=Line(dot1,dot2).set_color(WHITE).set_opacity(0.5)
               
            self.add(dot1,dot2,line1)
        #设置竖线
        for i in range(10*2+1):        
            dot3=Dot([(i-10)*5,-30,0]).set_opacity(0.5)
            dot4=Dot([(i-10)*5,30,0]).set_opacity(0.5)
            if i==10:
                line2=Line(dot3,dot4).set_color(WHITE).set_opacity(0.5)
                
            else:
                line2=Line(dot3,dot4).set_color(WHITE).set_opacity(0.5)
            self.add(dot3,dot4,line2)
        #设置三个点
        dot1 = Dot(radius=1, color=RED)  
        dot1.move_to([-47.5,27.5,0]) 
        dot2 = Dot(radius=1, color=YELLOW)  
        dot2.move_to([-42.5,27.5,0])  
        dot3 = Dot(radius=1, color=GREEN)  
        dot3.move_to([-37.5,27.5,0])
        #镜头跟进效果
        self.camera.frame.save_state()
        #题目出现
        text = Tex(r"$\int _{0}^{\pi }\dfrac{1}{1+\cos ^{2}x}dx $"
                   ,tex_template=TexTemplateLibrary.ctex).scale(5.0)
        self.play(Write(text))
        self.play(FadeIn(dot1),run_time=0.1)
        self.play(FadeIn(dot2),run_time=0.1)
        self.play(FadeIn(dot3),run_time=0.1)
        text1 = Tex(r"$=\int _{0}^{\frac{\pi }{2}}\dfrac{1}{1+\cos ^{2}x}dx+\int _{\frac{\pi }{2}}^{\pi }\dfrac{1}{1+\cos ^{2}x}dx$"
                   ,tex_template=TexTemplateLibrary.ctex).scale(5.0)
        text2 = Tex(r"$\lim\limits _{x\rightarrow \frac{\pi}{2}-}F\left( x\right) -F\left( 0\right)+F\left( \pi \right) -\lim\limits _{x\rightarrow \frac{\pi }{2}+}F\left( x\right)  $"
                   ,tex_template=TexTemplateLibrary.ctex).scale(5.0)
        #丝滑变化
        
        self.play(
            ReplacementTransform(text,text1)
        )
        self.wait(0.5)
        self.play(
            ReplacementTransform(text1,text2)
        )
        self.wait(0.5)

        text3 = Tex(r"$F\left( x\right) =\dfrac{1}{\sqrt{2}}\arctan \dfrac{\tan x}{\sqrt{2}}+c $"
                    ,color=GREEN
                   ,tex_template=TexTemplateLibrary.ctex).scale(5.0).move_to([0,10,0])
        self.play(Write(text3))

        text4 = Tex(r"$=\dfrac{\pi }{\sqrt{2}}$"
                    ,color=RED
                   ,tex_template=TexTemplateLibrary.ctex).scale(5.0).next_to(text2,RIGHT,buff=1)
        self.play(Write(text4))


